To investigate the role of ligustrazine on relaxation of the isolated rabbit corpus cavernosum tissue in vitro, the effects of ligustrazine on the corpus cavernosum were observed by using experimental method of smooth muscle strips. Concentration-responses to phenylephine (PE) and KCl were recorded. The results showed that ligustrazine concentration-dependently depressed the contraction response of smooth muscle strips induced by PE. The maximum percentage relaxation of cavernosal strips by ligustrazine was 74.1% +/- 6.2% (compared with control: 21.9% +/- 5.6%, P < 0.01). Ligustrazine concentration-dependently reduced the amplitude of the contraction induced by cumulative doses of PE or KCl, shifted the cumulative concentration response curves of PE and KCI to the right and depressed their maximal responses. It was concluded that ligustrazine could significantly relax the cavernosal muscle contraction induced by PE in vitro. The results suggested that ligustrazine inhibited calcium ion influx.
Calcium Channels/drug effects ; Muscle Contraction/*drug effects ; Muscle Relaxation/*drug effects ; Muscle, Smooth/*drug effects ; Muscle, Smooth/physiology ; Penis/*drug effects ; Penis/physiology ; Phenylephrine/pharmacology ; Potassium Chloride/pharmacology ; Pyrazines/*pharmacology

OBJECTIVETo investigate the effect of ascorbic acid (VC) on relaxation of ex vivo Bufo gastrocnemius during sustained isometric contraction.

METHODSDynamic tension of the muscle was recorded under constant voltage stimulation within 7.0 min at 2 s intervals. The rest tension and relaxation rate of the muscle was obtained by weighted fitting to the relaxation process of tension <90% of its peak with a mono-exponential model to characterize the muscular relaxation.

RESULTSVC at 2.0 mmol/L alone or in combination with the inhibitors of the antixoidation enzymes (surperoxide dismutase, glutathione peroxidase and catalase) resulted in negligible alterations in the muscular relaxation kinetics. VC combined with the inhibitor of surperoxide dismutase resulted in significantly lowered relaxation rate while increased rest tension, but VC with the inhibitor of either catalase or glutathione peroxidase showed negligible action. VC combined with the inhibitors of all the 3 enzymes also caused significant effect on the muscular relaxation kinetics, which was similar the effect of VC with superoxide dismutase inhibitor.

CONCLUSIONVC at high concentration may result in oxidative toxicity to the biological system rich in transitional metal ion complexes but with low antioxidation capacity by causing superoxide-mediated oxidative damages.

Animals ; Ascorbic Acid ; pharmacology ; Bufonidae ; Electric Stimulation ; In Vitro Techniques ; Isometric Contraction ; drug effects ; Muscle Relaxation ; drug effects ; Muscle, Skeletal ; drug effects ; physiology

AIMTo evaluate the relaxant effect of verapamil on human corpus cavernosum in vitro and to assess the drug's potential as a treatment for erectile dysfunction (ED).

METHODSPreparations of the human corpus cavernosum were obtained from recently deceased young men who had had normal erectile function. The isometric tension and detailed curves were recorded when contractions induced by 10 micromol/L phenylephrine were reduced by different doses of verapamil or the vehicle control (sterile water). The tension of human corpus cavernosum preparations are described as a percentage of their top tension before adding verapamil or the vehicle. ANOVA and least significant difference tests were used for statistical analysis.

RESULTSDoses of 1 micromol/L, 10 micromol/L and 100 micromol/L verapamil resulted in relaxation of (35.28+/-7.96)%, (55.91+/-6.41)%, (85.68+/-4.16)% after 30 min, respectively. The vehicle control at the same time point produced relaxation of (-0.06+/-10.57)% (P<0.05).

CONCLUSIONVerapamil is significantly effective in relaxing normal human corpus cavernous smooth muscle induced by phenylephrine in vitro and the relaxant effect depends on the concentration of verapamil.

Adult ; Humans ; In Vitro Techniques ; Male ; Muscle Relaxation ; drug effects ; Muscle, Smooth, Vascular ; drug effects ; physiology ; Penis ; drug effects ; physiology ; Verapamil ; pharmacology

Lotus( Nelumbo nucifera) is a traditional medicinal plant,and nowadays it is regarded both as medicine and food. It is widespread across China and rich in natural resources. Almost every part of N. nucifera could be used for medical or edible purpose,including seeds( Lianzi),black ripe fruits( Shilianzi),seed coats( Lianyi),green embryos of mature seed( Lianzixin),flowers( Lianhua),stamens( Lianxu),receptacles( Lianfang),leaves( Heye),leaf or flower stalks( Hegeng),leaf bases( Heyedi),rhizomes( Ou) and rhizome nodes( Oujie). Therefore,this plant is praised as a commercial crop with great economic values. Isoquinoline type alkaloids are the main chemical components of lotus. Smooth muscles usually exist in the digestive tract,respiratory tract and vascular,urinary,reproductive and other human systems. Dysfunction of smooth muscle contraction will induce many diseases including hypertension,asthma and gastrointestinal disorder,etc.,and most of current therapeutic strategies rely on relaxation of smooth muscle by drugs.Previous studies have shown that alkaloids of lotus have strong relaxation activity on smooth muscle. The present paper reviews phytochemistry and smooth muscle relaxation activity of 59 isoquinoline alkaloids from N. nucifera through accessing CNKI,PubMed and multiple databases for biomedical sciences.
Alkaloids/pharmacology* ; China ; Humans ; Isoquinolines/pharmacology* ; Muscle Relaxation ; Muscle, Smooth/drug effects* ; Nelumbo/chemistry* ; Phytochemicals/pharmacology* ; Plant Extracts

Ethanol has various effects on male sexual activity under the influence of direct and indirect, in acute and chronic alcohol ingestion. However, whether acetaldehyde, a principal metabolite of ethanol, may affect penile erection directly has still not been elucidated. This present study was, therefore, designed to clarify the pharmacologic effects of the acetaldehyde on corpus cavernosal smooth muscle. Corpus cavernosal strips were prepared from rabbit penises. Isometric tension changes of rabbit corpus cavernosal strips to various drugs and electrical field stimulation (EFS) in an organ chamber were recorded with a pressure transducer after active muscle tone had been induced by phenylephrine (10(-5) mol/L). At the concentrations employed, acetaldehyde had no effect on the pH of the bathing medium. Acetaldehyde in each concentration did not significantly affect resting tone of the smooth muscle during 30 min incubation. Acetaldehyde suppressed contractility induced by phenylephrine and KCI at 10(-4) mol/L, and relaxation induced by EFS and bethanechol at 10(-3) mol/L and 10(-4) mol/L respectively, but acetaldehyde enhanced relaxation induced by ATP at high acetaldehyde level. Sodium nitroprusside-induced relaxation was not affected at any employed acetaldehyde concentration. This suggests that increasing the acetaldehyde level may contribute to male erectile dysfunction mainly by the inhibition of nitric oxide formation.
Acetaldehyde/pharmacology* ; Animal ; Bethanechol/pharmacology ; In Vitro ; Male ; Muscle Contraction/drug effects ; Muscle Relaxation/drug effects ; Muscle, Smooth/physiology ; Muscle, Smooth/drug effects* ; Nitroprusside/pharmacology ; Penis/physiology ; Penis/drug effects* ; Phenylephrine/pharmacology ; Potassium Chloride/pharmacology ; Rabbits

Ethanol has various effects on male sexual activity under the influence of direct and indirect, in acute and chronic alcohol ingestion. However, whether acetaldehyde, a principal metabolite of ethanol, may affect penile erection directly has still not been elucidated. This present study was, therefore, designed to clarify the pharmacologic effects of the acetaldehyde on corpus cavernosal smooth muscle. Corpus cavernosal strips were prepared from rabbit penises. Isometric tension changes of rabbit corpus cavernosal strips to various drugs and electrical field stimulation (EFS) in an organ chamber were recorded with a pressure transducer after active muscle tone had been induced by phenylephrine (10(-5) mol/L). At the concentrations employed, acetaldehyde had no effect on the pH of the bathing medium. Acetaldehyde in each concentration did not significantly affect resting tone of the smooth muscle during 30 min incubation. Acetaldehyde suppressed contractility induced by phenylephrine and KCI at 10(-4) mol/L, and relaxation induced by EFS and bethanechol at 10(-3) mol/L and 10(-4) mol/L respectively, but acetaldehyde enhanced relaxation induced by ATP at high acetaldehyde level. Sodium nitroprusside-induced relaxation was not affected at any employed acetaldehyde concentration. This suggests that increasing the acetaldehyde level may contribute to male erectile dysfunction mainly by the inhibition of nitric oxide formation.
Acetaldehyde/pharmacology* ; Animal ; Bethanechol/pharmacology ; In Vitro ; Male ; Muscle Contraction/drug effects ; Muscle Relaxation/drug effects ; Muscle, Smooth/physiology ; Muscle, Smooth/drug effects* ; Nitroprusside/pharmacology ; Penis/physiology ; Penis/drug effects* ; Phenylephrine/pharmacology ; Potassium Chloride/pharmacology ; Rabbits

Acetylcholine ; metabolism ; physiology ; Animals ; Cholinergic Agonists ; pharmacology ; Male ; Muscle Contraction ; drug effects ; physiology ; Muscle Relaxation ; drug effects ; physiology ; Muscle, Smooth ; drug effects ; pathology ; physiopathology ; Rabbits ; Random Allocation ; Receptors, Cholinergic ; physiology ; Synaptic Transmission ; drug effects ; Urinary Bladder ; drug effects ; innervation ; physiopathology

OBJECTIVETo explore the pharmacological mechanism of Bazheng Mixture (BZM) in promoting diuresis and relieving stranguria.

METHODSBy means of urine collection through indwelling catheter and urethral ring isolation test to observe the effects of BZM on the urinary amount of conscious rabbits and contractile-relaxant function of urethral smooth muscle isolated from rabbits.

RESULTSBZM, at dosage of 5.0 g/kg or 10.0 g/kg by gastrogavage, could increase the urinary amount in 60 min obviously (P < 0.05). For the isolated urethral rings, the maximal contractile and maximal relaxant forces reduced significantly (P < 0.05 or P < 0.01) when the concentration of BZM applied ranged between 9.9-90.9 g/L; the frequency increased significantly (P < 0.05 or P < 0.01) when the concentration ranged 29.1-90.9 g/L and the amplitude increased significantly when the concentration were 56.6 and 90.0 g/L. Along with the concentration of BZM increased from 9.9 g/L to 90.9 g/L, the changes occurred in the above-mentioned parameters of urethral ring were in order of potency amplitude > frequency > maximal relaxant force > maximal contractile force.

CONCLUSIONThe effects of BZM in enhancing urethral peristalsis may be stronger than that in dilating the urethral caliber. Its mechanism in promoting diuresis and relieving stranguria may be related with its action of urethral dilatation and potential peristalsis promotion.

Animals ; Diuretics ; pharmacology ; Drugs, Chinese Herbal ; pharmacology ; Female ; In Vitro Techniques ; Male ; Muscle Contraction ; drug effects ; Muscle Relaxation ; drug effects ; Muscle, Smooth ; drug effects ; Rabbits ; Random Allocation ; Ureter ; drug effects ; physiology ; Urination ; drug effects

OBJECTIVETo investigate the vasorelaxant effect of taurine (Tau) in rat aortic rings and the mechanism.

METHODThe isolated thoracic aortic rings of male Wistar rats were mounted on the organ bath. The effect of Tau 10, 20, 40, 80 mmol x L(-1) on the rings with endothelium intact or endothelium denuded precontracted by the phenylephrine (1 micromol x L(-1)) or KCl (60 mmol x L(-1)), and the effect of Tau on the vessel reaction induced by various drugs were recorded with biological signal analytical system.

RESULTTaurine completely relaxed the contractions induced by KCl and phenylephrine in a concentration-dependent manner in endothelium-intact and endothelium-denuded rat aorta. Taurine attenuated the contraction to PE both in the absence and presence of calcium, but had no significant effect on the contraction induced by caffeine. The relaxant effect of taurine was significantly inhibited by pretreatment of endothelium-denuded aorta with potassium channel antagonists glibenclamide and tetraethylamine but not by BaCl2 or 4-aminopyridine.

CONCLUSIONTaurine induces an endothelium-independent relaxation in rat aortic rings. The mechanisms may involve the reduction in Ca2+-influx and Ca2+-release and the participation of the potassium channels (KATP and KCa, but not Kir or KV).

Animals ; Aorta ; drug effects ; physiology ; Endothelium, Vascular ; drug effects ; physiology ; Male ; Models, Animal ; Muscle Relaxation ; drug effects ; Rats ; Rats, Wistar ; Taurine ; pharmacology ; Vasodilation ; drug effects ; Vasodilator Agents ; pharmacology

Calcium channels exist extensively in the membrane of cardiac, skeletal, smooth muscle cell and neuron. Calcium channel blockers (CCB) were widely used for the treatment of cardiovascular diseases because they could relax vascular smooth muscle. Experimental researches on calcium channel blockers relaxing corpus cavernosum smooth muscle have been reported recently. Whether the blockers can be used for the clinical diagnosis and treatment of erectile dysfunction still need to be further investigated.
Animals ; Calcium Channel Blockers ; pharmacology ; therapeutic use ; Calcium Channels ; metabolism ; Cardiovascular Diseases ; drug therapy ; Humans ; Male ; Muscle Relaxation ; drug effects ; Muscle, Smooth, Vascular ; drug effects ; Myocytes, Smooth Muscle ; drug effects ; Penile Erection ; drug effects